The present invention relates to a manifold composed of a plurality of shells, for a multicylinder internal combustion engine.
In particular, the invention relates to a so-called three-shell manifold, in which a lower, an upper and a central shell are connected with one another on the edges, so that a plurality of inlet channels and a plurality of associated outlet spaces are provided. Each outlet on the engine block side opens into a separate, associated inlet channel of the manifold, which in turn continues into an outlet space. Generally, several inlet channels continue into a shared outlet space, in which the hot exhaust gases spread, expand and are cooled to some degree. The manifolds are exposed to extreme thermal stresses. These stresses are extreme in particular in the areas of the connecting weld seams between the shells and the wall sections which are impinged by the exhaust gas stream directly from the engine. Also, especially in a cold start, different sections of the manifold expand with varying degrees of rapidity and intensity, so that high tensions develop here in the areas of the weld seams.